1. Field of the Invention
The present invention relates to a lithium ion secondary battery, to a method for making an active material and electrode employed therein, and to an active material and electrode produced by the method.
2. Related Background Art
Many types of metal oxide particles (for example, SnO2 particles and the like), having larger charge-discharge capacities than carbon materials such as graphite, have been studied as negative electrode active materials for electrochemical devices such as lithium ion secondary batteries (see Patent documents 1-3 and Non-patent document 1-5, for example). However, using such metal oxide particles as active materials results in significantly lower cycle characteristics compared to carbon materials. The reason for this is believed to be that expansion and contraction of the metal oxide particles during the course the charge-discharge cycle causes dissociation of the metal oxide particles from the collector, thus interfering with conduction between the metal oxide particles and collector.    [Patent document 1] Japanese Unexamined Patent Publication No. 2001-143694    [Patent document 2] Japanese Unexamined Patent Publication No. 2002-110151    [Patent document 3] Japanese Unexamined Patent Publication HEI No. 6-275268    [Non-patent document 1] Electrochemical, Society, Vol. 140, No. 5, L81-L82(1993)    [Non-patent document 2] Electrochemistry, Vol. 72, No. 6, P. 452-454(2004)    [Non-patent document 3] Electrochimica Acta, Vol. 53, No. 179-185(2007)    [Non-patent document 4] ECS Transactions, Vol. 3, No. 9, P. 29-35(2006)    [Non-patent document 5] “Jisedai Jidoshayo Kouseino Chikuden Shisutemu Gijutsu Kaihatsu” [Project On Developing High-Performance Storage System Technologies For Next-Generation Cars] (Li-EAD Project), Abstracts from 2008 New Development Themes and Research Proposal Presentation, p. 6.